1. Field of the Invention
The present invention relates to a touch pad, and particularly relates to a hidden touch pad structure adopted for an electronic product.
2. Background of the Invention
With respect to FIG. 1 and 1A, a conventional lap top 1a with a touch pad 2a includes a base 10a, a cover 11a pivoted on an edge of the base 10a and a plate 12a disposed on an upper surface of the base 10a. The touch pad 2a is arranged between the plate 12a and the base 10a, and is partially revealed via a window formed in the plate 12a. The window in plate 12a is configured corresponding to the touch pad 2a. The plate 12a has a pressing member 121a inwardly extending from an outline of the window to press and retain against the touch pad 2a. The touch pad 2a has a lower surface aligned with that of the plate 12a for connecting a circuit board 12a arranged thereunder. The touch pad 2a electrically connects the circuit board 3a, and the exposed part of the touch pad 2a can sense user's finger effectively via the circuit board 3a to transfer and transmit signals therefrom. Generally speaking, the plate 12a has a thickness, of between 3 mm and 4 mm, greater than that of the touch pad 2a. To avoid height differences between the plate 12a and the touch pad 2a influencing the feeling of user's finger, the pressing member 121a has a smoothing surface 122a formed on a free end thereof. The smoothing surface 122a includes a graded curvature for smoothing touching.
However, the plate 12a with the window, the pressing member 121a and the smoothing surface 122a are manufactured by multiple steps, so as to increase costs and to reduce manufacturing efficiency. Furthermore, the pressing member 121a may be improperly long and reduce the size of the exposed part of the touch pad 2a. The pressing member 121a may be improperly thick to increase the height differences between the touch pad 2a and the plate 12a. The smoothing surface 122a of plate 12a is made within a small length of the pressing member 121a, and complicated steps are needed. Accordingly, designs of the pressing member 121a smoothing surface 122a are made carefully and manufacturing apparatus must be accurate and precise.
In addition, the touch pad 2a is opened up for use; a periphery thereof adjacent to the pressing member 121a of the plate 12a is easily covered with, and the exposed part of the touch pad 2a is stained with oil from a user's finger. Both are difficult to clean up and thus affect the long term life of the electronic product.
Hence, an improvement over the prior art is required to overcome the disadvantages thereof.